This invention relates to mechanisms which aid in inserting integrated circuit packages (IC packages) into the holes of a printed circuit board; and more particularly, it relates to mechanisms for straightening the terminals of pin grid array IC packages prior to their insertion.
In the manufacture of integrated circuits, a semiconductor wafer is processed by various steps that have been described in the art in order to produce a plurality of identical circuits on the wafer. After this processing is complete, the circuits are cut from the wafer and are individually mounted in respective IC packages that are generally made from plastic or ceramic.
One of the functions of an IC package is to provide a means for coupling the integrated circuit to printed wiring on a printed circuit board. To that end, each package contains a plurality of input/output terminals. These terminals are connected by conductors within the package to microscopic bonding pads on the integrated circuit die. Since the terminals are much larger and stronger than the bonding pads on the integrated circuit die, they are more suitable than the bonding pads themselves for making connections to the printed circuit board.
Over the past several years, the trend in IC packaging technology has been to increase the number of terminals on an IC package. A few years ago, standard packages contained just sixteen input/output terminals; whereas today, the number of terminals may exceed one hundred. Also, these terminals become bent and misaligned due to handling. This presents the problem of how to insert such a large number of terminals into a printed circuit board.
Prior art packages having only sixteen terminals were rectangular in shape, and eight terminals were located on one side of the package while the remaining terminals were located on the other side. Thus, all of the terminals could be manipulated by one's fingers as the terminals were being inserted into the holes of a printed circuit board. If some of the terminals did not align with their respective holes, one would merely push on them with his fingers to align the terminals during the insertion process.
However, when the number of terminals on an IC package gets substantially larger (i.e., exceeds fifty), it is impractical to place half of the terminals on one side of the package and half on the other because the length of the package becomes too long. Instead, the terminals are made to extend from the package in a grid-like array. This is called a pin grid array package.
In such a package, the array is square-shaped, and it has at least two rows of terminals on each of the four sides. Also, the terminals are generally quite close together (e.g., less than 0.125 inches). Thus, the outer row of terminals blocks access to all of the terminals on all of the inner rows. This makes it impossible to manipulate the inner row terminals with one's fingers, and difficult at best to manipulate them with mechanical tools while the package is being inserted into the holes of a printed circuit board. Even if just a few of the terminals are slightly bent and misaligned with their respective holes, the insertion process is a tedious, time-consuming job.
Accordingly, a primary object of the invention is to provide a means for straightening all of the terminals of a pin grid array IC package prior to their insertion into a printed circuit board.